The general avalanche hazard is MODERATE above an elevation of 9,000 feet and LOW below that elevation. Strong southwest winds, new snow loading and warm temperatures have created areas of unstable snow. At the upper elevations fresh wind slabs lie upon light density snow and sun crust. Weak faceted snow persist at the base of the snowpack on north facing slopes above an elevation of 9,000 feet. Human triggered slab avalanches are possible on steep terrain at the higher elevations. Avalanches are unlikely below an elevation of 9,000 feet.
Pockets of wind slab up to 18 inches in depth that were formed by southwest winds could be human triggered in steep, wind loaded avalanche terrain. If triggered on a north facing slopes above an elevation of 9,000 feet these slabs could step down through faceted snow to the ground.
Humans who venture into steep terrain that faces north above an elevation of 9,000 feet could trigger older slabs up to three feet in depth. These slabs lie upon a mid-October drought surface that is comprised of faceted snow.
( Discussion is generated from the previous day's afternoon forecast. )A Pacific storm system that is moving across Washington State is expected to rapidly move east across Montana and into the Dakotas on Friday. An associated cold front will move across our area in the morning. Snow and areas of blowing snow are likely overnight and through the morning. Diminishing snowfall with continued areas of blowing snow are expected in the afternoon. The snow level will descend from 7,000 to 5,000 feet after the passage of the front. This system will favor Yellowstone National Park and the northern portions of our forecast areas which could receive four to 10 inches of additional snow. Winds will veer from the west-southwest to the west at 20 to 30 with gusts to near 50 miles per hour on the higher summits.Human triggered slab avalanches one to three in depth are possible on steep, wind loaded slopes at the upper elevations. Avalanches are unlikely at the lower elevations. The general avalanche hazard is expected to be MODERATE at the upper elevations and LOW at the mid and lower elevations on Friday. A higher hazard may occur in areas with prolonged periods of intense wind drifting.
